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Report from the Academy Annual Meeting

This year's Academy meeting, held in Chicago at the same hotel as the 1992 ISPO World Congress, kicked off with some outstanding Thranhardt lectures. Each one was scientifically sound, clinically relevant, and very well presented by a member of the researcher team that undertook the original studies. Perhaps equally noteworthy, half the research reported dealt with orthoses.

Thranhardt Lecture Series

The first talk, and one of the Thranhardt Award winners, was by Stephania Fantone PhD and Andrew Hansen PhD, both from Northwestern University. Steph and Andy applied the Roll-Over Shape concepts originally developed to help quantify the results from dynamic alignment of prosthetic feet to stroke survivors wearing plantar stop AFOs.

The NU Roll-Over Shape [ROS] can be viewed as an engineering extension of Dr. Jacqueline Perry's concepts from clinical gait analysis of the foot rockers. The result of the ROS analysis is a depiction of the cam characteristics during stance phase of the net ankle-foot motion provided by a specific prosthesis or orthosis. This is a convenient and concise geometric method to summarize a complex series of motions, and one that lends itself to drawing clinical inferences that can be tested. Prior work with normals and transtibial amputees has suggested that the shape is relatively constant for each person.

This preliminary report looked at the ROS of a cohort of long-term stroke survivors who all wore custom thermoplastic AFOs with plantarflexion stops. Similar to other AFO-stroke studies, their results demonstrated that custom orthoses of this sort control plantarflexion well, significantly reducing the degree of gait asymmetry, but do not result in a full normal gait pattern. In this group, use of AFOs did not significantly increase gait speed. The ROS analysis was feasible, just as with prosthetic wearers, and raised clinical questions about the design of future AFOs for this purpose. In particular, it may be that an AFO with a longer effective anterior lever arm might result in increased gait stability. This talk included a very good discussion of the limitations of ROS as well as its potential advantages.

The second Thranhardt lecture was another very good presentation by Nicole Parent-Weiss CO, OTR, focusing in this instance on the use of the Halo CTLSO for toddlers three years of age or under. Pediatric halo applications are always a challenge due to the high activity levels, relatively poor balance and impulse control, and immature skull that characterize this population. Nicole did an excellent job of sleuthing the reasons behind the current guidelines for pin placement in peds and found little substantive science despite reasonable clinical consensus regarding the need for a non-standard vest and more pins applied at lower torques than with adults. The University of Michigan relies on a pre-operative CT scan to verify skull thickness in specific areas that may be pin sites and does not go more than two turns clinically beyond skull contact. In Nicole's review of 13 consecutive cases, all but one fused with a single procedure although 3 fell while wearing the Halo and were admitted to the Emergency Room for evaluation. Overall complications were very similar to those with adults, with minor pin tract infections being more common and generally managed with oral antibiotics. The U of M uses custom-made head rings for this group along with substantially customized vest and uprights, and often provides groin straps to reduce the tendency for the vest to migrate proximally.

Glenn Klute PhD presented a very entertaining talk about the effect of rest and exercise on residual limb temperature. Since complaints about heat and perspiration in a prosthesis are common, and moisture is well known to increase the risk of skin maceration, Dr. Klute taped an array of micro-thermistors to the RL while transtibial amputees engaged in exercise followed by different rest periods. The local skin temperature and percent of local blood flow were used as markers to indicate the likelihood of perspiration. One significant preliminary finding is that once the RL skin temperature becomes elevated, it tends to remain high despite one hour of rest. It may be important to avoid raising skin temperature in the first place, especially for dysvascular individuals whose skin is very fragile.

The final Thranhardt presentation, and the other award winner, was Brian Hafner PhD's discussion of the Prosthetic Research Study investigation into the transition by unilateral transfemoral amputees from a mechanical non-microprocessor-controlled [NMPC] to a microprocessor-controlled [MPC] knee. The PRS study was a very well structured multi-year crossover protocol. One key finding is that the accommodation period for experienced wearers of a prior mechanical prosthetic knee to fully adapt to a MPC knee varied widely and often exceeded one year. This raises questions about the validity of prior work with much shorter adaptation periods that showed only small differences between ambulation with MPC and NMPC knees. The PRS study included physical therapy to optimize function with both types of knee, so these results are of special significance.

There were a large number of favorable trends with the use of the MPC knee, particularly related to stability, but many were not statistically significant due to limitations in the number of subjects who could be recruited for such a lengthy study protocol. Fifteen of eighteen transfemoral amputees who had worn both prostheses long term preferred the MPC C-Leg and wore it 90% of the time, reserving the NMPC knee for specific activities. The PRS protocol included roughly equal numbers of both MCFL K2 and K3 ambulators and showed that half of each group increased one functional level once they learned to take advantage of the function offered by the MPC knee being studied.

The results from all of these preliminary reports are being prepared for publication and should appear in various peer-reviewed journals within the next year or so. Most will likely be published in the Journal of Prosthetics & Orthotics. The Thranhardt lectures have steadily increased in quality every year with very few exceptions and are rapidly becoming the "don't miss" presentations of every new year.

Debate: Cobb Angle versus Overall Balance in Adolescent Idiopathic Scoliosis

The Thranhardt talks were followed by one of the best orthotic sessions I can remember: a very spirited debate among a who's who of clinical orthotists about the best emphasis for the orthotic management of AIS. Marty Carlson CPO kicked off this session by reminding us that scoliosis pioneers such as Walter Blount MD focused on overall spinal alignment from a clinical perspective. However, as objective measurements such as the Cobb angle on the radiograph have become increasingly important in the ensuing decades, there is a tendency to "treat the X-ray" and to lose sight of the patient. Marty argued strongly that having a balanced spine is the most important clinical result from orthotic treatment of AIS. He proposes calculating an Overall Balance Summation [OBS] based on the measured deviation from C7 to the Central Sacral Line [CSL] on the X-ray, with rightward displacement being a positive number in millimeters and leftward a negative number.

Andrew Mills CO(UK) reviewed some of the concepts behind the SpineCOR "dynamic bracing" concept. He noted that the intention is to use the patient's ability to move to the desired posture for an active correction rather than the direct biomechanical support provided by the TLSO body jacket. Therefore, encouraging the head to become centered over the pelvis is an integral part of the SpineCOR philosophy.

Don Katz CO reviewed some of the research findings from his work at Texas Scottish Rite Children's Hospital. He recommends determination of tilt angles of selected vertebral bodies because this can add useful information beyond just the measured Cobb angle. Sagittal contours are also clinically important but sometimes underappreciated in the focus on obtaining Cobb angle improvement. Don's most recent study showed rather conclusively that between 30 & 40% In Brace Reduction [IBR] in the Cobb angle is predictive of successful orthotic management, lending support to the thesis that it is not the only key factor in treating AIS. Earlier research at TSRCH has shown that use of a TLSO to manage AIS is very dose dependent: the more faithfully the orthosis is worn, the better the outcome for most curves. Don has looked at a number of different ways to measure spinal "balance" but none could be shown to correlate with being able to avoid surgery. This supports the notion that it is reasonable to choose to provide less aggressive Cobb angle correction [so long as the IBR exceeds 40%] in return for keeping the head better centered over the sacrum.

Tom Coburn CO emphasized the importance of performing a thorough clinical examination prior to blueprinting the radiograph to create the orthosis. This insures that the orthotist can "see the patient" and not just the curve. He agreed with Carlson and Katz that both overall spinal balance and curve correction are important but sounded a cautionary note about limiting the Cobb angle correction to as little as 30%. Tom argued that if one could easily obtain 50% IBR or more without discomfort to the patient, that it would be worth making the added effort until the TSRCH work has been replicated.

During the discussion segment, Tom Gavin CO cautioned that the outcome that is being monitored has a profound influence on the results achieved: a variation on the aphorism "Be careful what you wish for...". He reiterated that the Cobb angle is only one possible objective measurement, and that it is neither the sole nor necessarily the most important outcome. For example, it may be that avoiding surgery is a more clinically significant outcome than a specific Cobb angle, although Tom pointed out that this has been a shifting target over the decades, gradually dropping from 60 degrees to 40 degrees as surgical stabilization improved and surgical risks have decreased. Miguel Gomez CO, MD reminded those present not to forget the transverse component of scoliotic curves, along with the more obvious coronal and sagittal manifestations, noting that for best results the orthotist needs to consider the three-dimensional characteristics of each individual curve.

Orthotic Free Papers

The orthotic free paper sessions began with another talk by Stephania Fatone PhD based on a simple model about the effect of incongruency between the anatomical joint and the orthotic joint. Using simple single axis models to represent both the biological and orthotic ankle joints, it appears that horizontal mal-alignment results in greater calf band displacement than errors in other directions. Steph's results were generally consistent with the theories promulgated by New York University in prior decades. Although this is very basic work, it is an important first step in establishing a foundation for credible scientific research about orthoses in the future.

Mathew Hughes presented a case report to illustrate the preliminary experience at Dorsett Orthopedics in England with custom-made silicone elastomer AFOs. The patient required orthotic intervention as a result of cerebral palsy and had previously worn solid ankle thermoplastic AFOs. The gait seemed improved on video compared to the plastic AFOs. Matthew reported a gradual improvement with the silicone AFO in the range of dorsiflexion, in active dorsiflexion ability, in the distance walked, and noted a 6 cm increase in calf circumference over a period of several months.

Keith Smith CPO wrapped up this session with a very nice case study of a young man who sustained a traumatic and complete Spinal Cord Injury [SCI] at the T10 level. He learned to ambulate with Isocentric TLSHKAFOs in rehabilitation, and then received new KAFOs using Horton's SCOKJ® to permit more normal swing phase knee flexion.

Subjectively, the patient reported much less effort with the SCOKJ® system and walked visibly faster in the video clips. It appeared that the SCOKJ® function reduced the need for the patient to lean laterally in an effort to clear the stiff contralateral leg with locked knee joints. Instrumented gait analysis documented that the patient's stride length and walking speed virtually doubled in the stance control mode even though this patient had absolutely no hip, knee, or ankle strength.

Exhibit Hall

Since the academic content of the Academy meeting has steadily improved over time, and the number of exhibitors has simultaneously increased, it is becoming increasingly impossible to see every item on every display table to offer a comprehensive review of the exhibit hall. So, the featured items in this report are simply those that caught my eye.

For the most part, the exhibit hall was filled with familiar items and "me too" knock-offs that provided no new functions. There was a novel quick-disconnect from Australia called a "UniJoint" that could be easily inserted in any 30 millimeter pylon system. A knurled tube clamp can be disconnected from the socket by the patient without changing alignment or length.

The buzz of the exhibit hall was clearly to two new powered OSSUR products since this was the first time most clinicians had a chance to look closely at these developments. Both the Power Knee™ and the Proprio Foot™ are the first externally powered active lower limb prosthetic components to be nearing commercial availability. While some of the details [including pricing] are still being finalized, many of the features of both products have been established.

The Prioprio Foot™ combines a carbon fiber composite dynamic response foot with a two pound electric ankle assembly that provides several different active dorsiflexion and plantarflexion functions. Not surprisingly, powered dorsiflexion after toe-off offers increase mid-swing toe clearance. While results in significantly abnormal kinematics [since the normal foot is plantarflexed approximately 10 degrees at mid-swing], based on the strong response to earlier mechanical technology such as the Hydracadence system, this feature is likely to be popular with many patients.

There is also a "relax" mode in which the foot slightly plantarflexes when the person is seated. This eliminates the "toe to the sky" appearance that is typical with solid ankle feet and reduces the risk that someone will trip over the prosthetic leg. If the patient wishes to have an extra range of dorsiflexion to make arising from the chair easier, tapping the toe signals the ankle to assume this position. Once the patient takes the first step, the ankle defaults back to stabilizing the foot in neutral and normal walking is facilitated.

The Prioprio Foot™ will also partially accommodate inclines and declines but changing the position of "neutral" but it takes a couple of steps for this process to be initiated. Finally, a manual heel-height adjustment is accessed when the patient presses the buttons on the ankle unit. Reportedly, 3-4 hours of recharge time will replenish the batteries sufficiently for a full day's use.

The attached video clip (wmv - 0.3 MB) illustrates the range and speed of motion of the Prioprio Foot™, which is the first externally powered prosthetic ankle-foot component.

The OSSUR Power Knee™ is the first component to offer externally powered active knee flexion and extension. Powered stance extension assists in ascending stairs, ramps and inclines. Powered swing extension is said to improve dynamic gait. Powered knee flexion increase toe clearance for walking on yielding or uneven surfaces. Details of the control algorithm were not available but other reports have said that sensors on the contralateral side measure how that leg walks and uses that data to control motion of the prosthetic limb.

Additional information on both of these products is posted online at Ossur Bionics.

Becker was showing another cleverly engineered knee orthosis from the Ambroise group in the Netherlands, called the Genux™. One of the innovations of this orthosis was the small plastic rollers that encircled the anterior thigh bands. Since the rollers pivot smoothly on the tubular anterior bands, the skin on the thigh is able to stretch freely as the knee flexes and extends without creating distal migration of the KO.

Suspension is provided by a garter-like elastic strap just proximal to the gastrocnemius muscle belly. Medial or lateral compartment unloading is modulated by shortening a flexible braided cable, which changes the genu varum or genu valgum angulation.

Additional information is available at Becker - Introduction to the Genux (PDF).

Finally, one of the surprise highlights of the exhibit hall was an impromptu harmonica solo by Rick Miller CO (wmv - 1.25 MB) prior to his talk about some of the products from Ortho Innovations that were developed from many years of real-world clinical experience. One of their more unique products is a portable casting frame, reminiscent of a Risser Table, that facilitates taking a highly accurate plaster impression for a custom TLSO. Use of this casting equipment makes the process far easier on the patient and the orthotist, not to mention the nursing staff, because it eliminates the need to log roll post-op patients. For additional information on this and other orthotist-developed products, visit Ortho Innovations.

If you're ever in the Rochester, MN area, you may be able to catch Rick on stage with the other members of Black Cat Bone. Being an orthotist in today's cost-containment environment, Rick has had plenty of experience with the blues!